SUMMARYA fatal case was described of a 41–year‐old woman with a tentative clinical diagnosis of acute viral meningoencephalitis of nine days' duration. The neuropathologic findings by light microscopy resembled those of acute necrotizing encephalitis or herpes simplex encephalitis, including eosinophilic intranuclear inclusion bodies of Cowdry type A. Electron microscopic study of these inclusions demonstrated the presence of herpes‐type virus particles. Though the titer of herpes simplex virus examined on the sixth day of the illness was not elevated and the isolation of the virus was not successful, the case was regarded as herpes simplex encephalitis clinicopatholo‐